An investigation into "skipping a beat" or skipping forward in video and au

Question

I've been researching this problem for months now as it was the biggest "ick factor" of the new computer I built. I'm creating this thread to document what I and others know about it, or at least think we know, so that maybe it will help us or ideally Creative to take a look into it.
Note: This thread only refers to the skip-ahead issue and may or may not address SCP.
See this post for some applications designed to diagnose and work around this issue.
The issue
Audio skipping a beat, videos jumping ahead.. This problem has many different names, and it describes a skip-ahead in media playback in the amount of typically between 300 milliseconds and a second. It can be subtle, so many users may not notice it or even care, but I've traced it down as far as I was able.
Please post here if you have this problem, along with what processor, motherboard, and sound card you're using. The processor and sound card seem to be the most important.
Why it occurs
You know about interrupts, right? Maybe you don't know that much about them. Neither do I, really. But they're the subject of much discussion when it comes to Creative's sound cards.
The Creative sound driver, by default, chooses to accept its interrupts on the first CPU available on the system. For some reason, when audio or video players aren't running on the same CPU or core as the sound driver accepts interrupts on, the system becomes prone to these skip-aheads.
In other words, video or audio players will experience no problems if they're running on CPU 0, the first CPU in the system. So with typical single-core processors, one should never experience an issue, unless perhaps they use hyperthreading which makes a single-core Pentium processor appear to have two cores.
Multi-core or multi-CPU systems running Windows (this post assumes Windows XP) by default allow running applications to be moved from CPU to CPU as the operating system or application sees fit, to put it simply. So your video or audio player may not always stay on the same core as the sound driver receives interrupts on.
But digging deeper into the problem, I was able to limit it to some specific modules, at least for video playback: the container splitter, and DirectShow. For standard AVI playback, quartz.dll should handle the splitting and DirectShow from what I understand, but if you're using a splitter such as Haali Media Splitter then both splitter.ax and quartz.dll must be using CPU 0.
How I tested this
I tried many, many, many things to solve this problem. I switched motherboards, graphics cards, processors, hard dri'ves, sound cards; reinstalled Windows, etc. It has happened with every configuration I've tried with one of my Creative sound cards, the Audigy 2 ZS or the X-Fi XtremeGamer, the same issue with both.
To aid in my testing, I created a Video Playback Tester application that uses a Windows Media Player object to monitor for skips in playback using a timer that checks the playback position periodically. It's a simple, hacked-together program written in C#, but I'll make it available to anyone who wants to use it for their own testing (let me know).
The first thing I discovered was that my onboard audio had no problems, while the sound cards did, and this was the same case for every configuration (motherboard, processor, etc.) that I tried.
So finally I was able to narrow it down to processor affinity. I ran several testers, set half of them to use CPU 0 and half of them to use CPU . Those on CPU had the random skipping, but those on CPU 0 were totally fine.
Shortly after this I learned of a tool known as the [url="http://support.microsoft.com/kb/252867">Interrupt-Affinity Filter Tool[/url]. It allows you to adjust on multiprocessor systems which CPU interrupts are received on. So, for my sound card, I tried setting it to CPU 0. This had no change from the default of either CPU; the effect was the same. So then, out of curiosity, I decided to try setting it to CPU . When I did this, the effect was reversed. Rather than CPU 0 having no problems, it began to exhibit the skips while CPU was fine. This is why I suspect a driver issue. After this, I reverted back to normal settings.
Using Process Explorer, I was able to see which the running threads of applications and which modules they were launched from. It was a bit of a daunting task, but I decided to incorporate this functionality into my playback tester in order to be able to set affinities on specific threads based on their module name.
The first thing I did was have it set every module's threads to CPU 0 except for one module. I ran several testers and had each one leave a certain module alone.
It was in this way that I was able to discover that with splitter.ax (my media splitter - Haali to be exact) left alone, the problem occurred. So then I ran a test with splitter.ax alone on CPU 0 and the rest left alone, and I was surprised to find that the problem still occurred.
Eventually, after testing a bunch of combinations, I was able to narrow it down to splitter.ax, quartz.dll, and dsound.dll, and after that I was able to eliminate dsound.dll, leaving the media splitter and DirectShow.
So.. what?
This post is mainly informational, but I'd like to know who else has these issues. To those that do, do you have an Intel Pentium processor that supports hyperthreading, or a dual-core processor? And which processor specifically?
I suggest you try the following and see if it eliminates the problem.
. Open your media player.
2. Right-click the taskbar and click Task Manager.
3. Click the Applications tab, find your player, right-click it, and click Go To Process.
4. Right-click the process and click Set Affinity... Now make sure CPU is unchecked and only CPU 0 is checked. Click OK.
5. Play whatever usually skips and see if it still does.
It's possible to work around this problem, but I for one would prefer a proper fix from Creative.
Let me know if it helps! Post what you know, what you've tried, etc.Message Edited by sireebob on 04-6-200707:48 PM
Message Edited by sireebob on 04-9-200705:42 PM

Answer 1

Thanks Jutapa.
When I ran the DPC Latency Checker, there were no significant hiccups, and nothing abnormal at all when the skips occurred. The PCI Latency Tool had no effect on the issue, either (I tried many different latency options, between 0 and 248). But maybe they'll help other people with this or similar problems!
Besides that, I tried logging huge amounts of data with the performance monitor and there's no consistent abnormalities at the times the skips occur as far as CPU usage or any other measurable variables go.
I'll check out http://musicxp.net! I'd tried fresh installs and disabling all unnecessary system services and startup programs before and it also had absolutely no effect, but that's probably not what MusicXP.net advises, so I'll take a look. Thanks!